text:
What is the reason for the different types of valve heads (mushroom, tulip, semi tulip) in reciprocating engines?
I am reading in the FAA-H-8083-32 Aviation Maintenance Technician Handbook-Powerplant book posted on the FAA site that there are engine valves with different types of head shapes, e.g. mushroom, tulip, semi tulip (image taken from flight-mechanic.com).

What is the reason for these shapes?

Related: Flight-Mechanic.com: Engine Valves

That part of the shape comes down to a couple of factors.
First of all, you want valves to be light. Second, the outside of the valve's head forms part of the combustion chamber.
The shape of the combustion chamber influences a couple of things. A hemispherical chamber tends to help "breathing"--the ability to get fuel-air mixture into the chamber and get exhaust out of the chamber.
Another common shape is a wedge. A wedge shape helps "swirl" the fuel/air mixture around in the chamber during the compression stroke, to ensure the fuel and air are evenly mixed, so it burns more evenly and completely.
The former tends to improve performance in terms of power per unit of displacement, while the latter tends to improve performance more in terms of power extracted per unit of fuel consumed.
A mushroom shaped head is typically (as shown above) used with a hollow valve. In this case, the valve is typically filled with sodium. Sodium is a metal with a very low melting point, so in normal operation, the valve is filled with liquid sodium. Liquid sodium is a very good heat conductor, so it conducts heat from the head of the valve to the stem, which is surrounded by oil and a valve guide, which help conduct the heat away. The mushroom head makes it relatively easy to maintain a uniform thickness of steel between the outside of the valve and the sodium inside, so the heat is conducted away relatively evenly--extreme heat gradients can lead to failure (e.g., the valve cracking). The valve's movement helps circulate the liquid sodium around to help heat circulation, and keep the temperature of the outside of the valve relatively uniform.
Another factor favoring a tulip shape (or similar) is reducing valve float. The heavier the valve, the stronger of a spring you need to ensure that the valve closes as soon as the cam lets it. If the valve stays open (floats) it can reduce power, or in more extreme cases the valve can contact the piston, which will normally lead to engine failure requiring a full inspection and rebuild at a minimum (and quite possibly requiring complete replacement). Stronger valve springs can help too, but they put more wear and tear on the drive train (e.g., timing belt) and "steal" more power from the engine to turn the cam.

Are there any citations for this information?


text:
What is the minimum speed for a scale-model of a modern commercial aircraft to fly?
Suppose a commercial jetliner (say an Airbus A320 or Boeing 737) were scaled down into  a remote-controlled drone, so that its wingspan were two feet wide. My questions regarding this scale-model are:
1) Would jet engines work if scaled-down to such proportions?
2) Would the wings, tailplane, ailerons, flaps etc. work if exactly scaled down in the same ratio as the fuselage?
3) At what velocity should the scale-model taxi in order to take off?
4) At what speeds should the scale-model fly to achieve stable flight, if the length and breadth of the wings etc. are made correctly to scale?
5) Is it possible that the flight speed of a scale model of a commercial airliner can be scaled down to the extent that it can realistically be remote-controlled by a person on the ground in a city environment, such as a park?
6) One of the things I am asking here is: can the plane shown in this video be genuine? Or is it necessarily a hoax, made with computer graphics?

The engines do not look like jet engines to me. It could be a hoax or illusion (not necessarily with computer graphics) or a real flying contraption but probably not a jet.

@Relaxed - It seems to be flying too slowly to generate any lift with those wings (which seem too narrow and too small to provide lift at that speed). Can you elaborate what you mean when you say, "or a real flying contraption but not probably a jet"?

If you scale down the structure of a modern airplane, it would work nicely. Since volume scales with the third power of length, but area scales with the second power, the wing loading would decrease with the scaling factor. Therefore, the dynamic pressure required to fly would also decrease with the scaling factor, as would all aerodynamic pressures. This means that all stresses within the structure will also come down, so the structural safety margin increases with the scaling factor.
What scales less nicely are the flow phenomena. The Reynolds number will come down with the 1.5th power of the scaling factor (1 power for the length and 0.5 power for the reduced speed), so the boundary layer would be relatively thicker. This would reduce the maximum lift coefficient and would make the gaps between the high lift devices of the wings (slats, flaps) too small to work properly. A simple logarithmic scaling law works well only over small changes and can not be applied here. After all, the scaling factor is close to 60. I would guess that the maximum lift coefficient is only half of what it is for the real aircraft, so the take-off speed is reduced by a factor of $\sqrt{0.5\cdot scaling\;factor}$. If the take-off speed of the original is 260 km/h, the model could take off at maybe 45 or 50 km/h.
This is quite a bit lower than the speed of the original aircraft, but still too high to fly it comfortably in a park. A wide open field would be more suitable.
At the same time, the relatively thicker boundary layer means the drag of the scaled aircraft is relatively higher, so the L/D of the aircraft comes down. Unfortunately, the flow inside the scaled gas turbines will also be negatively affected by the Reynolds number, so they will produce little thrust. In all, I am quite sure that the scaled Airbus or Boeing would not be able to accelerate to the required take-off speed since both drag increase and thrust loss due to scaling will make this impossible.
I saved the hardest part for the end. The flow in the tiny hydraulic lines would be thick as honey (but you could increase the hydraulic pressure by the scaling factor before the lines burst!), and scaling all control circuitry would result in electronic components which would cease to work completely.
In the end, my answer would be a clear no. It will require a lot of adaptions, and only then a scale model could be made to fly.

Suppose we make a concession, take out all the hydraulics and replace them with some combination of direct wiring, electronics, infrared/bluetooth/radio controls etc? As there is no need for the cockpit, which is replaced by the remote control console (which can be as intricate as a flight simulator cockpit is required), we can do without hydraulics and pneumatics.

Please check Question no. 6, which I recently added.

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text:
What are the advantages and disadvantages of level flight with a nose-down attitude?
This is a questions about fixed-wing aircraft in general -- commercial planes and smaller. I have seen on a video that planes are capable of flying in a holding pattern with an nose-down attitude "for greater passenger comfort".
So, what are the advantages and disadvantages of level flight (not descent) with a nose down attitude?
And for what reasons do pilots fly like this?

Generally, a slight nose-up attitude gives the best performance. This allows the fuselage to create some lift without producing too much drag, thus filling the drop in the spanwise lift distribution created by the interruption of the wing by the fuselage. However, in passenger aircraft this will make the job of attendants much harder because their trolleys need to be pushed uphill and will roll away when not secured.
Therefore, a neutral attitude is preferred in cruise. When the aircraft slows down, it needs to increase its angle of attack, so the nose-up attitude results. When flaps are deflected, the zero-lift angle of attack is reduced, so a smaller angle of attack will again be possible. The precise attitude is a side effect of speed, air density and flap settings, and is not deliberately controlled when flying a holding pattern. By this time the flight attendants have returned to their jump seats, anyway.
Note that some aircraft will fly a nose-down attitude by design. The Boeing B-52 has powerful flaps which are designed to allow it to lift off without rotating, and when the aircraft accelerates during the initial climb after take-off or flies its approach, the fuselage will have a nose-down attitude. See the picture below of the B-2, the B-1B and the B-52 all flying at the same speed, each with its own fuselage attitude.

B-2, B-1B and B-52 flying at the same speed (picture source).

Precise attitude is also affected by weight, so if an aircraft is designed to avoid flying with negative pitch, it will necessarily fly with some positive pitch when heavily loaded.

@JanHudec: The B-52 will be flown at its optimum lift coefficient, and its cruise altitude will be a consequence of loading - it simply would not climb any higher. At low speed, the loading is reflected in the choice of airspeed, and again the lift coefficient would be the same, regardless of loading. Thus, pitch will only change with loading if both speed and altitude are prescribed.

I mean more a typical airliner. But it's true they will also climb higher when lighter.

@PeterKämpf: ...as is typically the case whenever you're somewhere with air traffic control.

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text:
What are the advantages and disadvantages of having landing gear doors?
To make comparison easy, let us take the example of B737 and A320, both similar aircrafts with retractable landing gear.
As seen on the photo below, the B737 doesn't have gear doors for the wheels,

but the A320 does

Obviously, Boeing and Airbus made different choices for the same feature and both seem reasonable. Both aircraft models are well accepted by the airlines.
What are the advantages and disadvantages of both designs?
EDIT: I put links to other images where both aircraft are retracting landing gear after take off. The difference is obvious as we can see the landing gear doors operated for the A320 and no doors for the B737's wheel.

here is a better image of the lack of gear doors

@ratchetfreak  I prefer the images I originally linked (before the question was edited) because they show both aircrafts while the gears is moving and there is no ambiguity on whether the B737 has wheel doors or of it is a painting on the aircrafts body.

I've read in an Air & Cosmos magazine (french) that Boeing decided to go without gear doors (737-100/200) because of the design : ground clearance and belly volume. But I'm sorry, I've dumped the magazine long ago :/ Wether the Air & Cosmos article were correct or not, I don't know, sometimes they aren't. That's why this is a comment but NOT an answer at all.

The 737 does have gear doors.  It's just that those doors happen to be the wheels themselves.

Benefits of gear doors

With gear doors, there are fewer constraints on the retracted gear position. This is especially important in larger aircraft with larger and more complex landing gear. It doesn't need to be flush with fuselage or streamlined (737 also uses hubcaps).
The gear doors provide a good aerodynamic surface
Opening to gear bay can be larger and easier to access

Drawbacks of gear doors

Extra weight for the door and the mechanisms
Extra complexity of opening another door (possibility for things to go wrong)

"gear can be in the best position when retracted"  what is "the best position"

@rbp I tried to word that one better

How is fewer constraints necessarily a good thing, and why is it important in larger aircraft?

@rbp everything in an aircraft is limited by space and many other factors. The fewer constraints on a system, the easier it is to address other requirements. And as gear gets larger, it will have more components and take up more space, making the problem more complicated.

By saying "everything," you lose specificity, which makes that part of the answer nearly meaningless. You could have just as made it a drawback: "because space is required for gear doors under the fuselage, there is less space for cargo, etc."

@rbp With gear doors, the gear position is not constrained to one place. More options can yield better compromises.

I think part of the rationale behind the 737 approach was that the retracted gear is more compact - shallower wells, can be closer together without the space consumed by doors, hinges, and actuators

@fooot What about cooling brakes? Would lack of doors have any advantage?

Doors add weight and complexity to the aircraft, and need to be inspected and maintained. But doors also provide a smooth surface for the air to travel over, so they would have less drag. The 737 does have doors, but for the gear struts, but the wheels lay fairly flat against the fuselage, so drag is minimized.

Also note the exhaust from the packs looks like they come our right ahead of the tires, so they are at least putting drag sources in one place.

Also, in Boeing's case. it was decided to eliminate doors because they add COST.  When they were designing the 737, it was a relatively small, budget aircraft being built for regional service.

Could you expand a little? Somehow I find it difficult to believe that cost would be a major driving factor in this case.

You may enhance your answer by explaining why it differs between the A320 and the B737


text:
How do I translate this propeller start procedure into English?
I'm translating a documentary from Hungarian to English. There is a scene where the pilot of an aeroplane with a propeller is preparing for take-off.
He says (seemingly into a 2-way radio) two short sentences, literally: "Propeller pushing. Propeller free." Could anybody help me with info about what an English-speaking pilot would say in this situation. A million thanks in advance!

I assume that the propeller isn't turning at that moment. Before the engine start we say something like "Propeller Area Clear" to make sure, nothing is near the propeller while starting the engines. "Propeller pushing" I don't know...

You need to describe precisely what is happening and what the pilot is doing.  If there is a video link of some kind that you can provide, like youtube or liveleak, where we can watch what's happening, that would make it pretty easy to figure out.

@ymb1 If it's an AN-2 that would make a lot of sense.  But you wouldn't get me doing an hydraulic lock check with someone sitting in the cockpit :0

If the engine is already started, and if this is a turboprop with a constant speed propeller, it is most likely that the pilot is performing a pitch control check.  In this case the pilot would move the throttle into Beta, or reverse, which would momentarily cause the propeller to "push".  After this he would come back to idle, where if the propeller control lever was set to fine pitch or max RPM, the prop would spin "free".  The actual procedure and intercom voice calls will vary by aircraft and operator.
This answer presumes that he is not yelling out a window, or transmitting with aircraft callsign to a ground controller.  A video clip showing where he is on the ground, whether the prop is turning, and what his hands are doing at the time of the calls would confirm this.
If it is difficult to post a clip here, just watch what his right hand is doing:  If he appears to disengage a latch and pull the main power lever backwards, (you may hear an audible change in the engine sound as the propeller reverses pitch) and declares “propeller pushing”, then moves the lever back forward again and declares “propeller free” this would be pretty strong confirmation of my interpretation.
If that is the case, I might suggest a literal translation as you described in the question.  If you know the exact make and model of aircraft you could maybe narrow down what an English speaking pilot would say instead, but the literal translation wouldn’t necessarily be wrong either.

This is a perfect answer, thanks a million. The prop is stationary when the pilot speaks, but then he immediately starts it up. Before this there is a faint whirring noise, but it is only when the props start spinning that any engine noise can be heard. No one is outside the plane. I believe that your professional analysis matches my layman’s guesses and I’m going to go for “Propeller pushing. Propeller free.”  May all your flights take you to Cloud 9 and all your landings be happy ones!

Just out of interest: The topic of the documentary is not flying, but “Grief”. The pilot featured operates so-called “aerial funerals” where he scatters the ashes of the deceased from a few hundred feet. Most of the footage is of him demonstrating the special apparatus on one of the wings of his plane (“...a tilting container that can be opened by remote control or the push of a button. When it opens, the direction we’re moving in and the slipstream produce dynamic pressure, which pushes the ashes and the flower petals out of the opening at the back.”). Then of course, we take to the skies...

Or, in the case of the deceased, the heavens.

Very interesting, thanks.  Actually though, from your description it sounds more like he is starting the engine rather than the Beta check I described.  Still, I would probably just stick with a literal translation of the words and not try to read anything into his intent.

If this is in the context of starting the engine we would usually say, out of a window

Clear prop!

To ensure anyone standing close by is aware there's about to be a big dangerous spinney-thing near them.
If he is actually speaking into the radio, he may well be requesting startup clearance from a ground controller. eg pilot of airgraft registered "G-ABCD" to fictitious airport at "Airplaneville":

Pilot: Airplaneville ground, G-ABCD, Request startup
  ATC: G-ABCD, startup approved
  Pilot: Startup approved, G-ABCD

Another possibility is that the aircraft is being "hand-cranked" (ie, started by spinning the propeller rather than an electric starter motor). In which case there are various procedures but this text below describes the kind of communication between the pilot and the starter:

The starter−who by tradition is in charge−sets chocks in front of the wheels. The pilot holds back the stick and sets the throttle roughly a quarter of an inch forward from fully closed. The starter calls, “Switches off, sucking in”. The pilot shows a ‘thumbs down’, indicating that the rear magnetos are earthed. The starter acknowledges by repeating, “Switches off, sucking in,” and pulls the propeller forwards through four blades. (Always bearing in mind that there may be an electrical fault and the engine might fire.) The starter then sets the propeller, calls, “Set and contact,” and observes the pilot moving up the rear switches on both magnetos (the starter can see the switches, which is why they’re outside). The pilot gives a thumbs up and repeats, “Contact”. The starter swings the propeller and the engine starts. After an interval to allow the engine to warm up, the pilot crosses his arms, which is the signal for the starter to remove the chocks. (pilotweb.aero)

@ymb1 Thanks - the shame of forgetting to add my source.

Thank you for your selflessness, time and expertise. I only wish there was as much action in the shot as you have described - the clip lasts for about 5 seconds and is only intended to make a transition from being on the ground to being in the air. As indicated in my comment to Michael Hall, I'm now happy with the solution to my problem. I am now a great deal wiser and promise not to bother you again.

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text:
How to announce in an ATIS message that two parallel runways are in use?
Suppose an airport has two parallel runways and aircraft can use any of them.
How would I announce in the ATIS message that both runways are in use?

Hello Mhmoud, welcome to aviation.stackexchange.com! I've rephrased your question so that it is easier to understand. Please check if I interpreted your question correctly. If you want to make changes, please use the edit function.

By simply stating that both runways are in use.
For example, "arriving and departing runway 16 left and 16 right."


text:
When do pilots hold behind ILS Critical area?
I understand the puropse of the ILS critical area. But I have never operated at an airport having an ILS critical area. So I do not know when pilots hold outside the critical area but not at the RWY holding position marking.
Do pilots always hold behind ILS holding position marking?
Otherwise, pilots hold behind RWY holding marking and with a particular ATC instruction pilots hold behind ILS holding making?
If so, how will a controller instruct the pilots?
I want to know controller’s comments.

In the US (and you're looking at an FAA manual, so that implies US rules), this is covered in JO 7110.65, the FAA order covering air traffic control procedures. Flip to page 135 of that PDF (note that the linked version is not yet the currently effective version) for Section 3-7-5:

3−7−5.  PRECISION APPROACH CRITICALAREA a.ILS  critical  area
  dimensions  are  described  in FAA  Order  6750.16,  Siting  Criteria
  for  Instrument Landing Systems. Aircraft and vehicle access to the
  ILS  critical  area  must  be  controlled  to  ensure  the integrity
  of ILS course signals whenever the official weather observation is a
  ceiling of less than 800 feet or  visibility  less  than  2  miles.
  Do  not  authorize vehicles/aircraft to operate in or over the
  critical area, except  as  specified  in  subpara  a1,  whenever  an
  arriving aircraft is inside the ILS outer marker (OM)or the fix used
  in lieu of the OM unless the arriving aircraft has reported the runway
  in sight or is circling to land on another runway.
PHRASEOLOGY−HOLD SHORT OF (runway) ILS CRITICAL AREA

It goes on from there to describe further details, including instructions on when to keep the critical area clear and instructions to warn aircraft conducting autoland approaches if the critical area will not be protected.
In short, pilots hold short of the critical area if they're instructed to do so, and controllers tell pilots to do that by simply saying "HOLD SHORT OF (runway) ILS CRITICAL AREA."

Really appreciate, sir. It is a clear answer and did let me know where I should find if i have further questions.

The reason behind this: The radio signals from the ILS (mainly localizer) are slightly disturbed by anything conductive. And this gets more, the closer the aircraft is to the runway. When ILS is for precision approaches this can be too much to accept - so the airplanes will have to hold short a little more off the runway - which is the ILS critical hold...

This answer gives the reason for the critical area which seems to be clear to the OP. The question is looking for the procedure including phraseology.

Thank you, sir for the detailed meaning of the term!


text:
Which aircraft is this?
I was curious if someone could help me gather some more info on this aircraft.  I have looked it up in the FAA.GOV site and it does not match.  Is there a way to find out info on this plane that flew around the Springfield Illinois area around 1946, possibly before?  Also, this is a Stearman?  Is there anything else interesting or remarkable about this aircraft?  Thanks!

Looks like a Boeing Stearman to me.
I couldn't find anything based on the registration (NC55383) of the aircraft.

Source: wikimedia / scan from Robert L. Lawson (ed.): The History of US Naval Air Power. The Military Press, New York (USA), 1985. ISBN 0-517-414813, p. 72. US Navy cited as source.


text:
How long is a BAK exam valid for? (CASA Australia))
I am looking to get back into flying, and I passed my BAK theory in 2016. Is that still valid? I want to go straight to PPL so I will be doing PPL theory anyway, just would save me a step, unless I don't need it? Thanks.


text:
Could modern unmodified Airbus aircraft be used for zero-G flight?
ESA operates a mostly-stock A310 for their zero-G science flights, which doesn't have the flight envelope protection of more modern planes. Even then, a third pilot is required to monitor warnings to sort out the ones normally encountered in the parabolic maneuvers from unusual ones. If this aircraft were replaced with a modern Airbus (newer than A300/A310), would it be possible to fly these parabolic maneuvers without going into alternate law or doing other modifications to the control system?

According to this source and this source, the relevant A320 control laws (CLAWS) limitations are:

Normal load factor limitation in clean configuration down to -1g
Nose down pitch attitude down to -15deg
High Speed Protection (HSP) to prevent exceeding VD/MD

The problematic one would be the pitch attitude limiting. Since the pitch attitude will keep decreasing at zero G, the limiting function will pull the aircraft up and increase the load factor after some point. This could limit the time in zero G below the requirement.
Given the constraints and objective, more analysis would be needed to ascertain whether aircraft in Normal Mode is acceptable.

Actually not really. For one there are the protections in the software - but you must also take into account the cabin also needs to be a little modified to be usable for these kind of flighs. And possibly you'd also need to "tune" the fuel, lubrication and other related systems also...


text:
Are there any cameras inside a plane?
Are there any cameras inside a plane to watch out the activities of passengers?

related: http://aviation.stackexchange.com/q/11438/755

Yes

AIRCRAFT CABIN SURVEILLANCE SYSTEM
Surveillance system for aircraft interior (2002)
Surveillance Cameras In Aircraft Cabins (2002)

JetBlue Airways is the first U.S. carrier to get approval from the Federal Aviation Administration to install video cameras on all its airplanes.
  JetBlue is a successful start-up carrier based at New York's John F. International Kennedy airport. Soon after the Sept. 11 hijackings, the airline installed bullet-proof cockpit doors on all its planes. And it was the first carrier to match all luggage to passengers.
The airline has outfitted one plane with the video surveillance system, and plans to have its 23 other jets equipped with the miniature cameras within the next few months.
The cameras are positioned to cover the entire cabin. Some are visible, others are hidden so they cannot be tampered with

In-flight surveillance could foil terrorists in the sky (2008)

The European Union's Security of Aircraft in the Future European Environment (SAFEE) project uses a camera in every passenger's seat, with six wide-angle cameras to survey the aisles. Software then analyses the footage to detect developing terrorist activity or "air-rage" incidents, by tracking passengers' facial expressions.

A350 cabin surveillance contract (2012/2013?)

KID-Systeme has been selected to supply cabin surveillance equipment for the Airbus A350 XWB family of aircraft. The integrated solution will include both a cockpit door surveillance system (CDSS) and a cabin video monitoring system (CVMS).
  The CDSS provides pilots with a clear view of anyone in the area of the cockpit door, enabling them to take the appropriate action when entry to the cockpit is requested. The CVMS allows both the pilots and the cabin crew to view passengers.

Please tell me that the suggestion to install a camera in each passenger's seat to constantly monitor their facial expression is a joke...

@reirab "analyses the footage to detect developing terrorist activity" certainly sounds like it should be a joke, but I wouldn't be too surprised if it weren't.

@reirab I would certainly hope that some bad indigestion from that nasty burger & beer at the airport doesn't get someone tagged as a potential terrorist. A potential threat to local air quality, yes, but not terrorist.

@FreeMan I'm just waiting for the flight were all 300 passengers (and probably also most of the crew) are flagged as potential terrorists because the flight is delayed for 10 hours... then it gets further delayed to investigate the terrorist concerns, potentially resulting in actual air rage. - lol


text:
Is there any airline company owner who also works as a pilot?
Do you know any airline company owner who holds ATPL licence and flies one of the company's aircraft occasionally in normal operations just because (s)he likes to do it?

Shareholders are owners of the airline so it's quite possible that the answer is yes!

Define "Airline company". I'm sure there are plenty of companies that are a small plane flown by its owner-operator.

Bruce Dickinson is aiming to start an airline.
He is also a pilot and the lead singer of Iron Maiden.

Yes, Niki Lauda, former Formula 1 pilot and ATPL holder, founded Lauda Air, for which he also worked as PIC.

Lauda returned to running his airline, Lauda Air, on his second Formula One retirement in 1985. During his time as airline manager, he was appointed consultant at Ferrari as part of an effort by Montezemolo to rejuvenate the team. After selling his Lauda Air shares to majority partner Austrian Airlines in 1999, he managed the Jaguar Formula One racing team from 2001 to 2002. In late 2003, he started a new airline, Niki. Lauda holds a commercial pilot's licence and from time to time acted as a captain on the flights of his airline. Lauda Air ceased operations in July 2013.

Totally off topic, but gotta love Niki!

I was also going to comment saying Niki Lauda; he was the first one I thought of. He also took a personal interest in assisting with the LDA004 crash.

Although not an airline Howard Hughes was a test pilot for some of the Hughes Aircraft planes including the famous XF-11 that he crashed.
I can't find any information on if he ever flew any of the Hughes/Air West planes in a commercial situation or if he had a CPL but its worth mentioning.
Edit:
After some searching I did find this article which states

The only real job Hughes ever had also came in 1933. He signed on as a co-pilot for American Airways. He applied under the name Charles W. Howard. The ruse was quickly discovered, however, and Hughes resigned.

So it seems he did at least try to be a commercial pilot at some point although this was long before the Hughes/Air West Days.
Edit 2:
I forgot about it, but Joe McBryan the owner of Buffalo air a small freight and passenger airline in Canada and the focus of the History Channels show "Ice Pilots NWT" fly's some of the flights for the airline.
It also seems that Willie Walsh the CEO of Aer Lingus and then British Airways was a 737 captain however it does not seem that he held these positions while being a captain.
Collett Everman Woolman one of the founders of Delta Airlines (and eventually the CEO) did fly for them when them when they were a crop dusting business (and legally an airline) but I cant find any info on if he flew passenger or mail flights for them.
Walter Varney the founder of both Continental and United Airlines was an airmail pilot for United at one point (possibly also during passenger operations.
Leon D Cuddeback another founder of United Airlines is credited as flying the first airline flight in the country so I'd say he makes the list.
A Felix duPont one of the founders of Allegheny Airlines (eventually US Airways) was a test pilot for Focker and an aviation enthusiast as well as serving during WWII for the Air Transport Command although it does not seem that he flew commercially. His brother Richard Chichester duPont was also an aviation enthusiast and founder of Allegheny Airlines although its unclear if he ever flew for them he does hold some aviation awards.
You can find a list of US based airlines here and the rest of the world here if you want to continue cross referencing owners who were also possibly pilots. It seems that a lot of the early founders/pioneers in aviation were also founders of airlines.

Niels Sundberg, the founder, owner and CEO of EZ (Sun Air of Scandinavia, a franchisee for British Airways) was also a captain for his airline with over 13,000 hours. He was forced to retire from flying paying passengers at 65 under EU regulations, which he describes as big blow.
http://delightmagazine.dk/niels-sundberg-the-sky-is-my-passion/&prev=search
(In Danish)

The Discovery Channel TV series Flying Wild Alaska included COO Jim Tweto who would fly some flights as well (as I remember, mostly bush plane flights).

King Willem-Alexander of The Netherlands occasionally moonlights as a pilot for KLM. Does that count?
The royal Fokker has just been purchased by Alliance Airlines of Australia and replaced by a B737, I presume king Willem will continue to pilot KLM 737s every now and then.

he's not an owner of KLM so wouldn't count (unless he personally holds some KLM stock, something that's not in the public record).

KLM means Royal Dutch Airlines...

I know... That does not mean they are owned by the house Royal. In the Dutch system the term "Royal" for a company is an honorific granted to the company for quality service to the Royal family, not an indication that they are owned by them. KLM is owned 100% by Air France for example.

David Eyerly was a cofounder of Surf Air in California. He was a graduate of Embry-Riddle held multiple ratings, and frequently flew the company's Pilatus PC-12s as PIC.

Bruce Dickinson, Iron Maiden's singer is a qualified Boeing pilot (and a champion fencer). He co-founded Astraeus Airlines, which was a charting and wet/dry leasing company. Bruce flew for them, and when Iron Maiden rented one of their 767s (christened Ed Force One), he flew it.
https://en.wikipedia.org/wiki/Iron_Maiden#Ed_Force_One


text:
When can a pilot disobey ATC commands?
The title really asks it all: When can a pilot disobey ATC commands?.
Of course, the pilot has the final decision, but when would the pilot really disobey someone in ATC with much more knowledge of planes and other potential hazards near by?

Others will chime in with much better and documented answers, but ultimately, the pilot has final authority. If ATC tells it to crash into a cliff or another aircraft (we'll suppose that would be unintentional, of course), he/she has every right (to put it mildly) not to do so.

Another less dramatic illustration would be an ATC instruction for a VFR flight to climb or turn into a cloud. This happens all the time as a radar scope doesn't show clouds, so the VFR pilot would have to reply "unable" and hopefully give a reason, after which ATC will issue new instructions (probably climb/turn "when able").

There are two examples on YouTube, at least one of which has also been discussed here. Maybe someone can dig out the links. In one case, a pilot was issued a clearance he deemed risky, and asked for a different one, only to be pressured by the controller to take that clearance or leave it. The pilot then threatened to declare an emergency and do what he deemed necessary for the safety of the flight, which would have led to an investigation, not to mention screwing up the whole sequence, after which the controller backed down and issued the clearance the pilot had originally asked for.

The other case happened at Geneva, I believe. An airplane got lost while taxiing, and despite telling the controller numerous times that they were lost and that someone had just taken off directly in front of them (i.e. they believed to be on or near an active runway), the controller not only insisted that they were wrong and they couldn't possibly be anywhere near where they said they were, but issued a takeoff clearance for an airplane on the very runway the lost plane was just about to cross. The pilot replied something like "Until you figure out where that plane is, we are going nowhere."

@JörgWMittag It sounds like you're thinking of this one? That was in the US, but something similar could easily have happened somewhere else too.

Jörg Can you provide links to those YouTube examples?

@TomMcW: https://youtu.be/-sQuHnrJu1I

@TomMcW: https://youtu.be/_cl7SgpvTG8

In case of emergencies, yes. The pilot in command has the final authority and responsibility for safety of the flight and can disobey ATC commands in case of emergencies. The reasons for that and the results will decide the consequences.
From 14 CFR §91.123 Compliance with ATC clearances and instructions:

(a) When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory.
(b) Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised.

From 14 CFR §121.557   Emergencies: Domestic and flag operations:

(a) In an emergency situation that requires immediate decision and action the pilot in command may take any action that he considers necessary under the circumstances. In such a case he may deviate from prescribed operations procedures and methods, weather minimums, and this chapter, to the extent required in the interests of safety.

Emphasis mine. Obviously, it would be prudent for the the pilot (and required under FAR 91.123(c), as @Pondlife points out) to report the deviation to the ATC as soon as possible.

Note that it isn't just prudent to inform ATC about what you're doing, it's required by 91.123(c)

Interesting to read that "only" persons are bound to ATC instructions. What about the Autopilot? Is it a "person" in a transitive way?

@hiergiltdiestfu in what way are you expecting the autopilot to deviate from ATC commands? It only does what the pilots have programmed into the FMC - if deviation from that is necessary, the pilots switch off the AP (either hit the switch or pull on a control long enough for it to automatically disengage).

@FreeMan Well, I don't know.. I was mainly thinking about the whole Google self-driving car debate about who is responsible if the car crashes -- the occupant, the engineer who programmed the AI, the manufacturer of a sensor to blame? The regulation talking explicitly about persons seems to open up a loop hole with respect to (semi-)autonomous systems.

It would be a shame (and waste!) if we spent thousands of hours training pilots how to handle all these obscure scenarios only to have them yield to under-informed ATC controllers when an emergency actually occurs.

@hiergiltdiestfu the autopilot isn't truly an autonomous system or an AI though. Ultimately, the pilots set the autopilot and are expected to monitor their flight path and take action as necessary. The regulation talks about persons because the crew, not a machine, is responsible for following clearances. If the crew has to deviate from a clearance because a semi-autonomous system has somehow "gone wild" due to a fault, that could well be an emergency.

When I started college I was studying aviation; there were role-plays and simulations where we would have to make the call whether or not to deviate in given situations. Those were interesting discussions....

A pilot can break any rule in the book for the safety of the flight or those on the ground. Ultimately the safety of the flight rests with the pilot in command of the aircraft and therefore not just the right but the duty to diverge from ATC instructions if the situation warrants. Examples of this might be:

A cabin depressurization or engine failure requiring an immediate descent
A change in course or altitude to avoid a collision with an aircraft or terrain
Passenger illness
Unlawful interference
When intercepted by law enforcement or the military
If complying with an instruction is hazardous, for instance putting the aircraft outside its flight envelope, into a possible collision
Fuel emergencies
Mechanical problems

In cases such as these pilots will take immediate action and inform ATC afterwards if they can.

"Fuel emergencies" -- so they could land without clearance when running out of fuel and ATC not caring about it?

@hiergiltdiestfu, when you run out of fuel, you will land. The only questions are A) where and B) under how much control. No, ATC won't "not care", but they understand you have to get on the ground now.

If you are in an airplane that's running out of fuel then you can land without clearance, however you shouldn't have to. If you declare an emergency ATC will help you and make sure the way is clear.

@hiergiltdiestfu To add to what Freeman says, if you are running out of fuel and you need to get on the ground now, you will be declaring an emergency. ATC will then do whatever you need to get the aircraft safely down. Afterwards you will probably get a phone number to call and a very stern talking to from an individual at your nearest FSDO.

I see. Thanks to all who were so nice as to show me the true nature of fuel emergencies. I kind of forgot that this is nothing that comes as a surprise, but develops gradually, such as that you'll have time enough to communicate beforehand

To add one more case to what's been mentioned, if ATC tells you to climb to avoid a conflict and TCAS tells you to descend, pilots are required to follow the TCAS command rather than ATC's.
The reason behind this is that TCAS in the two aircraft can typically coordinate "behind the scenes" which aircraft will do what in order to avoid a collision, but there's no guarantee that both aircraft are hearing the same plan from ATC. Maybe separate controllers both issue a "climb" command, or one aircraft is on the wrong frequency, or whatever. But the TCAS-to-TCAS communication is sufficiently reliable that this is now a required (although extremely rare) case of disobeying ATC.

This was (one of the) factors in the Überlingen crash.

It's not the only reason. En-route RADARs have a scan period of 10 seconds. That means controllers have a stale picture. When TCAS goes off, then it's too late (and dangerous) for ATC to interfere. When a pilot reports "TCAS RA", ATC can't say anything to the planes, (traffic information included) until pilot reports "clear of conflict".

@Stelios, ATC can absolutely continue to give traffic information and even control instructions to aircraft responding to an RA. We just can't give any instruction contrary to that RA.

@randomhead I beg to differ and I'm afraid I'm not the only one From the answer: When informed, ATC doesn't provide further instructions to this aircraft before receiving the "clear of conflict" confirmation.

@SteliosAdamantidis, you realize that you're telling an actual ATC controller his job, by quoting an internet posting at him, right? I tend to give credence to the specialist who is doing this stuff daily, over the interpretations of those who aren't. Though that may be just me.

Oh I'm sorry @RalphJ, they are a person who anonymously claim they are an ATCO and I know (with my first and last name public) that the ATCOs that I have worked with do it as I say. Please let me know if you think my comments have offended you and I will remove them. Again sorry if I have offended anyone.

Others have talked about emergencies, which allows a pilot to take any action he sees fit. This is correct, and you could even argue that it's not really disobeying, as in the moment the emergency was declared, all clearances sort of went out the window.
There's one important part missing and that's the option for a pilot to not accept a clearance or an amendment. A clearance is not an instruction as much as it's a negotiation, and once established, is more or less valid until both pilot and controller can agree on something different. If they can't agree, by either the pilot saying "unable" for whatever reason, or in the case where radio communication is lost and the pilot didn't actually hear anything, he is expected to carry on as previously cleared.

I know pilots can refuse a LAHSO clearance.


text:
Why don't some airlines assign seats to passengers?
Why don't some airlines (for example Southwest in US) assign seats to passengers? How does it help them? Doesn't it delay the boarding (passengers going back and forth inside the plane to grab their favorite seats)?
Are there any studies to show that this is a better method? Or is there any technical reason why some airlines does this while others do not?

I am not sure this is answerable with facts rather than just guesses.

Passengers generally enter the plane from the front. They won't be going back and forth; they'll go as far as they want and grab some seat. And people with reservation in the back trying to pass others trying to take a seat in the front may make just as much delay.

If I was to guess, I'd say because it makes the reservation system simpler. Still, many low-cost airlines started out that way and started reserving places later, but usually the reason given is that it was not well received by passengers.

There are some passengers that prefer not having reserved seats. If we use Southwest as an example, it allows travellers to puchase tickets fairly close to the day of their flight, and then merely check-in online 24 hours before departure to get the best boarding group and then show up early and and line up early to get the best pick of seats. Contrast that with booking the flight early to get the best reserved seat and then being able to show up later and enter the plane last to get the reserved seat.

I vote to close because this question can't be answered with facts or any other information-source. Provided answer's may be primarily opinion-based or assumptions.

I forget where I saw it, but there was a (probably unscientific) study where a plane was loaded a few different times a few different ways and the results were compared. They loaded front-to-back, back-to-front, and "free-for-all". I can't recall the results, though...

Apparently it was Mythbusters. Their conclusion was the fastest way to board a plane is the "free-for-all" method, but passengers also liked it the least. http://flightclub.jalopnik.com/mythbusters-proves-most-airlines-board-planes-all-wrong-1636981904

@Steve There have been more scientific studies done that showed back-to-front loading of window seats, then middle, then aisle to be the fastest of alternating rows, IIRC. This, of course, makes perfect sense, as everyone is putting their bags up at the same time, rather than the guy in row 3 blocking the entire plane for 5 minutes as he attempts to shove his bag in the overhead. As far as boarding time is concerned, front-to-back (assuming boarding from a forward door) is the least efficient, due to aisle blockage. However, airlines do it anyway because it makes their elites feel special.

@Steve While the optimality of the above-mentioned method seems kind of obvious to me, it apparently has been studied by some guy named Steffen and is referred to as the 'Steffen method.'

I don't believe this is opinion based question. There has to be some studies backing the decision of airlines going this route. All I'm asking the community is let me know if they have come across those studies. I couldn't find them when I searched online.

Short answer: make more money ( charge for seats selection, online reserve system, etc......)

southwest doesn't charge for seat selection.. Also when you charge for seat selection, you are assigning the customer seats. I'm talking of airlines not assigning seats..

It is mainly used by low-cost single-class cabin airline companies to make the reservation process simpler.

How does it make the reservation process faster. Would you as a passenger care if you are getting an assigned seat but the process take few seconds more? If it makes reservation process faster, why is it only used by low cost airlines.

I think "simpler" here mainly means "simpler for the airline" - they don't need to [pay software developers to] keep track of which seats are filled, just a count of how many seats are filled. Similarly, they don't care about the layout of a different planes; for the purposes of reservations every plane can be boiled down to a single "capacity" number.


text:
As a plane gets slower, why does a certain bank angle make you turn faster?
In the video "Maneuvering during Slow Flight" the narrator states that while flying slow the airplane will be less responsive to aileron and other control inputs. He also says that the plane will turn quicker at a certain bank angle than it would if the plane was flying at normal speed. My question is: why does the plane turn quicker when flying at a lower speed?
So basically what I am asking is, as a plane gets slower, why would it start turning faster then it was when in fast flight?

The part of the video I am confused about is at 1:16

Rate of turn is dependent on the following two items:

The horizontal component of lift (centripetal force)
The tangential velocity of the aircraft (true airspeed)

The rate or turn is directly proportional to the horizontal component of lift and inversely proportional to the tangential velocity of the aircraft.
For a given angle of bank, the vertical and horizontal components of lift will be the same, regardless of airspeed in level flight.
Consequently the airplane will experience the same centripetal acceleration, regardless of airspeed.
Since the tangential velocity is slower, any kind of centripetal force will produce a greater rate of turn for a slower flying aircraft as opposed to a faster moving aircraft and this can be shown by the centripetal acceleration equation
$$a_c = \frac{v^2}{r}$$
so both slow flying airplane with a true airspeed $v_s = 100$ knots and fast flying airplane with a true airspeed $v_f = 200$ knots experience the same centripetal acceleration.
$$\dfrac{v_s^2}{r_s} = \dfrac{v_f^2}{r_f} = 4\ \dfrac{v_s^2}{r_f}$$
or, $$\dfrac{1}{r_s} = \dfrac{4}{r_f}$$
Consequently  $r_s < r_f$; in this case $r_f = 4\ r_s$
Since the angular velocity is equal to the tangential speed divided by the radius.
$$\omega = v/r$$
the angular speed of the slower aircraft will be greater than the faster aircraft.
$$\omega_s = v_s/r_s$$
and
$$\omega_f = \dfrac{v_f}{r_f} = \dfrac{2 \  v_s}{4 \ r_s} = \frac{1}{2}w_s$$
So our twice as slow airplane turns twice as fast as the faster one does under these conditions.

@Krumia Only variables should be typeset in italics, therefore the indices need to be contained in \mathrm{...}

@bogl "should" according to? Remember that this is not a scientific publication with editorial guidelines.

According to improved readability. I would have used "shall" if it was mandatory. Note that my comment addressed @Krumia, because he put some effort into beautifying your answer, and I voted on his edit. Anyway, feel free to roll back.

You can see this same phenomenon in a car, no?  Try making a turn at top speed vs. a slow one.  Good luck making a 90º turn at 80 MPH!  But we do it all the time at 5-10 MPH.

It's there, but a car does not have a horizontal force component, only tire friction controls turn.  But (infinite disclaimers), if you slam on brakes and wrench the wheel to skid/spin the car (without flipping it), you can turn faster. Skid and rollover limit car turns, not planes.

But the principle remains the same.

Another way of explaining it in simpler terms would be:
Two vehicles, driving at 10m/s and 100 m/s respectively, both execute 180 degree turns to the left.
The catch is that each car must do the turn so that the driver only experiences 0.5G lateral acceleration.
For the car traveling 10m/s this will mean a turn radius of 20m.
This car will complete the turn in just over 6 seconds while covering 62.8m.
For the car going 100m/s, a turn radius of 2000m will produce the same sideways force.
It will complete its U-turn in 63 seconds while covering a distance of 6283m.
In short, the slower moving car can make a U-turn much quicker.
The same thinking can be applied to flying.

Got to clue you all in on something, a car in a turn does not skid.  This analogy, though well liked, is inaccurate in that it does not reflect the physics of turning in air in 2 ways. First the sum vector of forward motion and horizontal component of lift vector is the direction of flight.  Secondly, the tail pivots the aircraft through the turn.  Cars are attached to the ground, their turn rate is limited by the friction of the tires on the ground.  The 100 m/s car would turn faster if it could pivot.

The key word is "rate" of turn. It means that if you are travelling slower, it will take less time to complete a 360 degree turn than if you were going fast. It's the same as when driving a car.
If you want to complete the turn quickly at a high speed, you need a steeper bank angle compared to the angle you'd need at a low speed.

I don't see how this answers the question. The question was "given a constant bank angle, why do you turn faster when flying at a slower speed?" You've given a clear explanation of what "turn faster" means, but you don't seem to have said anything about why.

@TannerSwett I took a guess that the OP had simply misunderstood what was meant in the video, and did not need a detailed explanation of the physics. I felt that the existing answer, whilst accurate, could have confused him if he did not have a strong understanding of physics. So I gave a simple answer which hopefully helps him understand the concept, even if it doesn't fully explain the 'why'.

Yeah, that makes sense. I think this is a good answer in that case.

A steeper bank angle and higher g load ...

Weight does not change for different speeds, so lift does not change, too, if you maintain the same bank angle. At lower speed, however, the kinetic energy, the direction of which needs to be changed in a turn, is smaller, so the same lift force has less work to do.
A banked wing creates a side force which is used as the centripetal force in a turn. This force is actually pulling the aircraft sideways into the new direction of movement. When banking into the turn, the centripetal force will accelerate the aircraft sideways and will decelerate its original speed component, such that the direction of the speed vector continually changes while its scalar value stays constant. If there is less speed to convert, turning can be made more quickly.

The most intuitively understandable answer, while still being correct.

I hope you mean "work" in the figurative sense... ;) Ideally, lift never performs any work.

@Sanchises "has less work to do" also means "overcoming fewer opposing forces" I think.

@KorvinStarmast In physics, the term "work" is exclusively reserved for energy transfer in the form of force times distance. Plain English is not that strict; so you are of course right - I was just being pedantic in a semi-joking manner.

@Sanchises Yeah, this is the internet and Pedantry 'R Us.  8^D

It is more about momentum than kinetic energy. Ideally, the kinetic energy remains constant during the turn.

@VladimirF The answer is treating the kinetic energy as a vector quantity, and decomposing it in the original direction of flight.

@Sanchises which is wrong.

@VladimirF: I was thinking about mentioning momentum but found the explanation with kinetic energy easier to understand. My goal is not the answer with the most exalted vocabulary but one that is easy to understand. I agree that the momentum explanation is physically correct. But when a wing "has work to do", explaining it in terms of energy suggests itself.

@Peter Kampf may I suggest:  the centripetal force will accelerate the plane sideways and DRAG will decelerate its original speed component... it's scalar value stays constant (due to constant thrust).  Notice if the plane banks but does not pivot,
thrust component stays in the same direction and plane will track a diagonal.  Pivoting thrust in a new direction allows drag to slow original speed vector.

@RobertDiGiovanni: Drag and thrust cancel each other and the sideways component of lift is indeed the force which reduces the original speed component. Why else would the aircraft bank all the way through its turn, even right before the end when the new speed is almost achieved? At the beginning of the turn lift mostly builds up new speed while at the end it mostly reduces the old speed. This is described by the development of the sine and cosine functions: They tell you what part of the force adds new speed (sine) or reduces old speed (cosine).

Ok, I was thinking of rolling into the bank, but arresting the yaw with rudder. This is a side slip.  Without crosswind, and no rudder input, the horizontal lift component, pulls the plane sideways, activating the yawing motion from the tail (straight wing).  No power added, descending turn.  Opposite rudder, descending slip moving into the bank, diagonal descent.  With cross wind, straight descent.  The aircraft maintains its bank through the turn from differential lift of wings, the tail turns the nose.

But now I see!  As the plane yaws, drag AND horizontal lift component slow and stop travel in the original direction.  Thanks!  I was not seeing instantaneously (no pun intended)

And BTW amount of lift differential needed to hold bank (and how it is created) is another great subject!

Please pardon my one-liner: because it is very hard to turn a speeding bullet.

Same bank angle => same turning force. Much less inertial energy to turn around when the plane flies slowly.

When you turn, acceleration is used to redirect your direction of travel. If your initial velocity is low (slow flight) then less acceleration (bank angle * time) is needed to redirect your travel.
If your initial velocity is high (SR-71 Mach 3.2 flight) then more acceleration (bank angle * time) is needed to redirect your travel.
Bank angle describes acceleration here because it effectively revectors some portion of "lift" into a horizontal direction, which causes the change in direction.
Of course flying straight and level, the lift is used to exactly counteract the force of gravity.  In a level turn, some of the wing's lift is used to cause the direction of travel to change (horizontal acceleration), and also back elevator is added to increase the angle of attack, and cause a temporary increase in lift while turning.  (That might slow you down a little in the turn by the way.)
So the simple answer is that there is less energy (acceleration * time) spent in turning a slow object than a fast object.

A slower plane at a constant bank angle will have to fly at a higher AOA to maintain the same
amount of lift than the faster one.  At a constant bank angle vertical and horizontal lift components are distributed in the same ratio fast or slow.
Why does the slower one turn quicker?  Because of increased drag at higher AOA, there is more resistance to forward motion, while the side profile is identical to the faster one.
The slower one has equal lateral acceleration to the faster one (horizontal lift component) but less forward motion.  The resultant vector (direction of flight) is more in the direction of the turn.  Notice lateral G forces are the same.  In order to do this the faster plane must turn slower!
Also skewing the result in favor of the slower, increased elevator deflection, turned sideways in the bank, helps turn the aircraft faster.
Finally, the prop blast over the tail surfaces (thanks John K) also creates greater turning forces.
The wing pulls the plane sideways, the tail turns it.  Add power in a slow turn.

authors: Vladimir F Героям слава


text:
How can an international MRO apply for FAA approval?
I own a small maintenance, repair, and operations (MRO) shop in Indonesia. We are having trouble with our customers that required us to obtain FAA approval in order to get order from them.
I already tried to ask the Indonesian regulator to help us to obtain FAA approval, but no luck. FAA requires an MRO to maintain at least one N-registered aircraft, and we don't have any in here.
Does anyone have same experience? And how can we proceed?

These 14 CFR Part 145 Forms might be the forms you are looking for however there may be other forms for applying from overseas.
This site (FAA Aircraft Repair Stations Homepage) has some good links and here are the pre application regulations you need to comply with.
Here is the letter of the law of the FAA regulations (Starts at Title 14 Section 145.1).
I am no lawyer and cant really comment on this but I have no idea how FAA regulations work outside of the country and how/what foreign entities must comply with. I would advise contacting a local lawyer as well as a US lawyer about this.

If you could supply some relevant search terms in case the FAA or EFCR web sites get rearranged, that would make this answer much more useful in the long term.

Are there any special lawyer or agency that specialize in this field? Which one?

You can try contacting the FAA directly (not quite sure how to do that), as for a lawyer I would look for someone who has some experience in the aviation world. Maybe someone who worked for a firm that has handled an airline or maintenance facility already.

You need to apply for foreign FAA Repair station certificate under PART145 to your nearest Foreign FASDO (Flight Standards District filed office) . There are several steps one must take for compliance as per regulations including training.


text:
What is different between a Cat IIIA, Cat IIIB, and Cat IIIC ILS approach?
In terms of aircraft equipment, approach minimums, procedural differences, and anything else relevant, how do the 3 types of a Cat III ILS differ from one another?

You may narrow your question as a simple search on wikipedia gives lots of information and great references to answer a significant part of your question.

ICAO and FAA CAT III definitions
A CAT III operation is a precision approach at lower than CAT II minima. Sub-categories are listed below.

A category III A approach is a precision instrument approach and landing
with no decision height or a decision height lower than 100ft (30m) and a runway
visual range not less than 700ft (200m).
A category III B approach is a precision approach and landing with no
decision height or a decision height lower than 50ft (15m) and a runway visual
range less than 700ft (200m), but not less than 150ft (50m).
A category III C approach is a precision approach and landing with no
decision height and no runway visual range limitation.

*I've omitted the JAA definitions.
Source Airbus Flight Operations Support documentation.

FAA Reference Material
The below links are to comprehensive FAA publications covering the areas as titled.
FAA AC120-29 for CAT I/II.
FAA AC120-28 for CAT III.
Thanks @Sports Racer for the comment with links to these documents.

Also see FAA AC120-29 for CAT I/II http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-29A.pdf and FAA AC120-28 for CAT III http://www.faa.gov/documentLibrary/media/Advisory_Circular/120.28C.pdf

It might not hurt to move them into your answer. Sometimes things in comments get lost.

It may be worth to note than in Europe CATIIIb is 75m-200m RVR, and DH <100ft. CATIIIa is the same as FAA in Europe. EU-OPS-1 page 81, Aerodrome operating minima, (g) Precision approach — Category III operations

From: AC 120-118
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_120-118.pdf
CAT I (FAA)
An instrument approach operation with a minimum descent altitude (MDA), decision altitude (DA), or decision height (DH) not lower than 200 feet (60 m) and with either a visibility not less than ½ SM, or a Runway Visual Range (RVR) not less than 1800 feet (550 m).
CAT I (ICAO)
Any precision approach and landing operation with a DA/H of 60 m (200 feet) or higher and with a minimum visibility of 550 m RVR or greater will be termed a Standard CAT I operation.
CAT II (FAA)
A precision instrument approach operation with a DH lower than 150 feet but not lower than 100 feet and a RVR not less than 1000 feet.
CAT II (ICAO)
Standard CAT II operations are made to a DA/H below 60 m (200 feet), but not lower than 30 m (100 feet), with associated RVRs ranging from 550m (1800 feet) to 300 m (1000 feet).
CAT III (FAA)
A precision instrument approach and landing operation with a DH lower than 100 feet (30 m) or no DH, or a RVR less than 1000 feet (300 m).
CAT IIIa (ICAO)
A precision instrument approach and landing operation with a DH lower than 30 m (100 feet) or no DH and an RVR not less than 175 m (600 feet).
CAT IIIb (ICAO)
A precision instrument approach and landing operation with a DH lower than 15m (50 feet) or no DH and an RVR lower than 175m (600 feet) but not less than 50m (200 feet).
CAT IIIc (ICAO)
A precision instrument approach and landing with no RVR limitations.

Most recent European Law (so at least applicable in Europe):

A "type A instrument approach operation” means an instrument approach
operation with a minimum descent  height or decision height at or
above 75 m (250 ft);
A "type B instrument approach operation” means an instrument approach
operation with a decision height below 75 m (250 ft). Type B
instrument approach operations are categorised as follows:

Category I (CAT I): a decision height not lower than 60 m (200 ft) and with either a visibility not less  than 800 m or a runway visual
range not less than 550 m;
Category II (CAT II): a decision height lower than 60 m (200 ft), but not lower than 30 m (100 ft) and  a runway visual range not less
than 300 m;
Category IIIA (CAT IIIA): a decision height lower than 30 m (100 ft) or no decision height and a runway  visual range not less than 175
m;
Category IIIB (CAT IIIB): a decision height lower than 15 m (50 ft) or no decision height and a runway  visual range less than 175 m, but
not less than 50 m;
Category IIIC (CAT IIIC): no decision height and no runway visual range limitation;’.

https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R0401&from=EN

Cat III A 600 feet (180 meters) Runway Visible Range (RVR)
CAT III B 150 feet (46 meters) RVR
CAT III C zero visibility

No decision height in any CAT III approach (CAT II is 100' and CAT I is 200')

A Cat IIIA approach can have a 50' DH for operators that need one.  Not sure how wide or narrow that set of operators is, though.

Also please note that specifications differ here between FAA and ICAO. These figures are FAA-figures (which may very will be what the OP wanted)

Quite. So I don't appreciate the negative vote!

You may consider editing the answer to a more readable format.

There's also the Alert Height, Read more in FAA AC120-28. http://www.faa.gov/documentLibrary/media/Advisory_Circular/120.28C.pdf


text:
Can you identify the plane with number NC 14959 photographed in Boston in 1937?
I have a photo of a plane with the number NC 14959 taken in Boston on December 31, 1937. The hanger behind it says "Occidental Airlines".
I am trying to find out what kind of plane this is?
I am sure of four things:

the date,
the NC registration number,
that it was taken at Boston, MA
the photographer's name is Carleton Parker, a prominent Boston area train photographer who photographed extensively from the late 1920's to the early 1950's, primarily trains but an occassional aircraft.

Post the photo?

It is a Lockheed Electra 10A, and, by good fortune, quite a famous one now admired by hundreds of people every day. Details on the Electra Survivors Project. It was delivered to Eastern Air Lines on 24 September 1935.
It was later re-registered NC5171N and can be seen today in the Science Museum in London, displayed in the 'Making the Modern World' exhibition (as opposed to the aviation section). Its prominence there derives in part as being the same type as Amelia Earhart's aircraft on her final expedition, as well as the same type that British Prime Minister Neville Chamberlain used on his return to England after the ill-fated Munich Conference. (Note, this was not the actual aircraft in either of those events - but it is the one in your photo.)
 source


text:
How is the transfer of an aircraft managed when it landed at a different airport than the scheduled one?
The question came to me when my flight could not land at the scheduled airport because of fog.
We landed in a nearby city (Turin instead of Milan). Is the aircraft transfered without passengers later on? Bear in mind that there are no flights scheduled between the 2 cities (120 Kms distance only).

Hello Paolo, welcome to aviation.stackexchange.com

The aircraft will most probably be re-positioned to wherever it is needed. Often this will mean sending a crew to wherever the aircraft is and having them ferry it empty. If it is some far-flung place, the crew which landed it there may wait until it is possible to re-position it themselves.


text:
Are there aeromedical reasons to avoid too-rapid descent in hypoxia?
I recently watched this video:

When the controller realized the pilot was hypoxic (at about 9m47s in the video) they said,

Kalitta 66 if able descend and maintain FL260

but 26000 feet is still very high and provides insufficient oxygen. I (an ignorant student pilot) would not expect someone to recover from hypoxia at that altitude.
I realize it's possible the controller had other reasons to slowly descend the plane, but are there specifically aeromedical reasons for a gradual or slower-than-emergency descent into richer-oxygen air in this kind of situation?

There are no aeromedical reasons to descend slowly due to hypoxia.
Also, the controller did not know for certain that the pilots were hypoxic due to a loss of pressurization. All the controller knew was that they were in an emergency situation and seemed to be having difficulties.
The descent to FL260 was not gradual. It was a normal descent. The controller probably only controlled the airspace down to FL260, or there could have been another aircraft in the area at FL250. Kalitta 66 was further cleared to 11,000’ once clear of any conflicting aircraft. We didn’t hear the entire ATC conversation, but I bet Kalitta 66 was cleared to 11,000’ BEFORE they reached FL260, so in reality, it was probably a normal descent from FL320 all the way down to 11,000’.
An ATC controller can not order any aircraft, in any situation, to execute an emergency descent. ATC can only provide clearances and instructions to insure ATC separation. Sometimes a controller will ask a pilot to “expedite descent” but a pilot can only accommodate that request if it is safe to do so.
There is an old story about an ATC controller asking a pilot to expedite his descent and reach a certain altitude at a certain point. The pilot responded “unable”. The controller then said “Don’t you have Speedbrakes”? The pilot answered “Yes, I do, but speedbrakes are for MY mistakes, not yours”.

Does Air Can routinely give high altitude indoc courses to flight crews?

High altitude physiology is occasionally covered during recurrent training, but there is no training in a hypobaric chamber.

I got a chamber ride at DCIEM in Downsview in the early 80s, with a group of skydivers going for high alt jump certification. It was only a ride to 25000 ft to experience hypoxia symptoms, no decompression demo. My initial hypoxia symptom was tunnel vision, then euphoria.  When I reconnected to oxy, the symptoms vanished in a couple seconds.  My buddy was a chain smoker, and he went into nitrous oxide-like giggle fits within about a minute.  When I was drawing my shapes on the clipboard, I remember they were lopsided, and I knew they were lopsided, but I didn't think that was a problem. Weird.

To be clear, we don't know of any aeromedical reason. There are a lot of physiological mechanisms interacting there, and they are not that well understood.

Or that controller only owned the airspace down to ~FL260 (FL245 is a common boundary) and had to coordinate with another sector before giving lower.

@JohnK there's a bit in this after 6:30 where he's told to put his mask back on and turn on the oxygen or he'll die, and he just says "I don't wanna die" then does nothing while sitting there smiling (controlled environment, not actually at risk). Very eye-opening. https://www.youtube.com/watch?v=kUfF2MTnqAw

@llama I dimly remember reconnecting my oxy line by myself when a kind of drunken sensation welled up, intense enough to startle me (we were primed in the briefing to do that - the chamber tech in the box with us was a kind of safety backup).  I kind of wished I'd let it go longer to see what happened.  I've had nitrous at the dentist and the effect is similar.  My giggly chum was totally out of it by a couple minutes in and had to be reconnected by the chamber tech (I think there were 6 or 8 of us in the box).

@llama I watched it and I'd say I was like the first guy but I lasted longer, and my chum was like the host who had to to have the intervention, but as a heavy smoker he went into the goofy stage a lot sooner because I remember him giggling before I even noticed any symptoms.

You could say there is a "technical" aeromedical reason for descending slowly, not related to hypoxia directly, but you shouldn't be flying at all if it exists and there's no way a controller could know about it, and the pilot would likely not know about it either until he tries it anyway.
That would be sinus cavities that are unable to vent due to inflammation. Air escapes a lot easier than it can get in, so if you have blocked sinuses you will likely be unaware on the ride up as air is able to get out.  The problem starts when it has to come back in.
The effect of 4 or 5 or 6 psi squeezing your sinus cavities is like a migraine x10. Unbelievably painful (I've experienced it descending from 8000 ft to 1000 ft with blocked sinuses I was unware of until the sensation of a freight train parking on my face started).  This why every pilot should carry a bottle of a fast acting sinus decongestant like Otrivin in their brain bag.
Putting all that aside, I'd say that the controller, once he'd deduced what was going on, decided to coax the pilot down, knowing that if the pilot was in uphoria stage, the last stage before you pass out, he wouldn't respond to an attempt by the controller to raise alarm bells, and not having the authority to order the pilot to start an emergency descent, that was the only option available.
Probably the initial request of FL260 may have been an attempt at "baby steps" less likely to get the pilot confused or questioning with the first descent instruction and he gave it knowing he would modify it once they were established in a descent.
Of course the problem is the if the pilot had passed out right after starting the descent, with the ALT setting at FL260, the plane would have leveled off there as the autopilot captured the flight level, then slowed down (the engines being at idle) until the autopilot kicked off as the plane approached stall, then it probably would have eventually started a spiral dive until the crew came-to or the plane broke up. Hard to criticize the controller's decision in the heat of the moment though, and it worked.

Yes, once wile descending I suddenly had a sensation of someone driving nails into my forehead, could not clear via "Vasalva" maneuver, fortunately was flying a powered plane not a glider, could solve the problem by climbing immediately, then continuing Vasalva maneuver.  Never recurred again.  And at other times have had no problem dealing (via Vasalva maneuver) w/ the much greater pressure changes associated w/ descending while swimming, snorkeling, or scuba diving.

I just recently had Omicron, and the after effect was sinus inflammation, which I deduced because I was getting nasty headaches that I eventually realized were coming on when good weather approached, with maybe a 2 or 3000 foot equivalent altitude change as a high moved in.  I couldn't tell other than the headaches from pressure changes.  My doc prescribed a nasal steroid anti-inflammatory that cleared it up after a couple of weeks.

Valsalva maneuver

There are no diving medical reasons limiting the descend speed of scuba divers as long as they are able to equalize their ears as fast as necessary. Descending from surface to 10 m depth with double surface pressure is possible in a few seconds.
Ascending to surface after the dive should be slow to avoid decompression sickness.


text:
Can you identify this aircraft?
This photo, taken circa 1939, was taken of my uncle's aircraft at Roosevelt Field on Long Island, New York.  Lotar Munch and his partner operated "Munch & Romeo Flying Service" out of Hanger 32. I'm trying to learn more about his business and his aircraft as well.  Note the registration number "NC966V."  I have learned that the "C" indicated that it was a commercial registration. Any help would be much appreciated!

https://1000aircraftphotos.com/Contributions/Shumaker/12098.htm  (Even the same tail number:  Its a Westbrook W-5 Sportster)

http://all-aero.com/index.php/56-planes-v-w/17398-westbrook-aeronautical-w-5-westbrook-aeronautical-sportster

P.S. All I did was google the tail NC996V, and follow the first half-dozen links.
I'm sure you could've done that yourself.

As some have written in the comments, it is a Westbrook W-5-B Sportster.
Westbrook started as a company in 1929 and failed in 1931. Approximately five W-5 sportsters have been built:

[NC9N] c/n 501 destroyed in a 1931 crash
[853W] c/n 502,
[NC966V] c/n 503 lost in a 1938 accident
[NC92V] c/n 504,
possibly unlicensed one,  c/n 505,

source / further info: aerofiles.com / secretprojects.co.uk / all-aero.com

Munch & Romeo, Inc
The aircraft was shown on the business card of Munch and Romeo, which also shows the prices they charged for flight instruction:

I found evidence that one of the aircraft of Munch and Romeo was  involved in a mid-air collision in 1936:

Negligence -Collision -Insufficient Allegation of Agency.
-[NewYork]  In an action for damages arising out of a collision between
the plaintiff's airplane with that of the defendant as both were about
to land,the complaint alleged that the defendant's plane was being
operated by one Donahue with the consent and permission of the
defendant, and that the collision was caused solely by Donahue's
negligence. On motion to dismiss the complaint for failure to state a
cause of action, held: complaint dismissed, with leave to plaintiff
to serve an amended complaint within ten days.There were no
allegations that Donahue was operating the defendant's airplane as
his agent, servant or employee, or in the defendant's business
and within the scope of his employment. None will be inferred from the
allegation that the defendant was the owner of and in control of the
airplane.An allegation that Donahue was operating the vehicle with
defendant's con-sent and permission would be sufficient to charge the
latter in a case arising out of an automobile collision on a public
highway under §59 of the Vehicle and Traffic law, but the statute is
not applicable here. Consequently the common law rule governs, by which
it is settled in New York that the owner of a vehicle will not be held
liable for negligence of its operator unless at the time it was being
used in the owner's business by the operator within the scope of his
employment. Munch & Romeo, Inc. v. Caton, 96 N. Y. L. J.876, 235 C. C.
H. 1213 (County Court, Nassau County, New York, Sept. 25,1936).

source: Journal of Air Law and Commerce, Volume 8|Issue 1, Article  8 scholar.smu.edu

The company owned other aircraft as well; by 1936 they seemed to be active in aircraft trading as they tried to sell several aircraft in advertisements in Aero Digest, Volume 29 of July 1936

AERONCA C-3: New September 1935; 150 hours  total time ; just top
overhauled, A-l condition  throughout, SI. 425. Munch & Romeo, Inc.,
Hangar  7, Roosevelt Field, Mineola, New York.

1936 TAYLOR CUB: 2 months old, 35 hours total  time, \$1,195. Gee Bee,
Kinner K-5: 45 hours since  overhaul, \$875. Avian Cirrus, \$600. Also
Great Lakes,  Birds, Cessnas, Monocoupes. Munch & Romeo, Inc.,  Hangar
7, Roosevelt Field 1 , Mineola, New York.


text:
What should be the thrust weight ratio for takeoff?
I am doing some calculations for preliminary design of an airplane and I was wondering how I would go about determining the minimum thrust to weight ratio needed for the aircraft to takeoff. Which factors play a role and how are they limiting the thrust to weight ratio?
I admit the question is vague but it is intended to be that way.
My team and I are tasked with building a Distributed Electric Propulsion based aircraft and the only other requisite apart from it being fully electric is that it must have a wingspan of at least 3 ft. Everything else is completely up to us to estimate and design.
I am looking for guidance on what factors I have to consider or what mathematical methods I would have to employ in order to estimate a necessary Thrust/Weight ratio

Minimum wingspan of 3 ft points to a drone. Is that really the only prerequisite this student work (?) has. Surely there are some metrics that will be used to evaluate your work against others?

This could be reopened, but please, please, add more detail. A lot more. Do your basics first.

Without knowing more about what you are designing it is impossible to come up with a specific number.
But there are a number of factors that you should take into account:

the lower the thrust to weight ratio, the longer it will take to accelerate, so the longer the required runway will be. During the take-off roll the lift can usually be neglected, but the parasitic drag and roll drag will increase with speed. The faster you go, the slower you accelerate. You need to have enough thrust to achieve your take-off speed within a reasonable distance.

at take-off, the thrust still needs to exceed the drag, otherwise you will have no excess power available to climb.

after take-off, you typically need to achieve a certain rate of climb and a certain climb angle to clear obstacles. This is affected by the thrust to weight ratio. If you require a climb angle of 10°, you need a thrust to weight ratio of $\sin(10°) \approx 0.17$ just for the climb, even if you have no drag. With a lift to drag ratio of 8 at take-off conditions, you would end up at a thrust to drag ratio of at least. $\frac{D}{L}+sin(\gamma) = \frac{1}{8}+sin(10° )\approx 0.3$

you may want to achieve a certain top speed with the aircraft. Check what the thrust to weight ratio is required in those conditions. It may be higher than what is needed for take-off.


text:
Can anyone explain me the ILS Approach Chart of my Airport?
I'm from Lucknow, India (VILK) and recently I experienced my very first CAT IIIB  ILS landing at my homebase. Ever since I'm more curious to know about this technology and how it works.
I was able to get the charts of various approaches type at my base but I was interested in the ILS CATII/IIIB type but I don't understand a single word mentioned in the chart.
My flight took 4 holding patterns at 11000 feet just like how its drawn on the chart and then we flew towards east and descended to 7000 feet on our initial approach and then turned south and finally west to runway 27 at 3000 to 2500 feet and continued at 2350 feet for sometime and then descended to land.
The arrow over airport looks exactly how we took made four holding patterns before landing exactly like its drawn in the chart but I don't understand if what I'm making of it is actually what it is or not.

Let us continue this discussion in chat.

One thing that seems to make it easier is the arrows point to the compass direction.  It was confusing at first that the landing seemed to be to the east.  I was wondering if the "11000 foot holding pattern" was drawn in or did you just descend and enter the 3500 foot bearing 089 min oval?


text:
Unarmed F-16 -- why would it happen?
As is documented here among other places, a couple of the interceptors sent after United Flight 93 on September 11, 2001 were scrambled so hastily they did not have time for the ordies to visit and arm them up.  While not having live missiles on you at all times makes sense for a variety of reasons -- I can't understand why a fighter jet would be flying around with 0 rounds of ammo for their gun, considering how much of a W&B impact the ammo load has.
Furthermore, even if the media coverage was referring to them being loaded with training slugs instead of live ammunition -- you can seriously damage an airplane with 20mm slugs, as one Grumman test pilot (among other folks, it seems) found out the very hard way!  Sure, you'd have to use quite a bit of cannon fire to do it, but it'd still be preferable to a last-ditch ramming attack, no?
So, how could a fighter be scrambled into a situation where their only option was to ram their target?

I'm not sure I follow the question. "Why" was pretty apparent, they needed to prevent another attack. "How" was also pretty simple, get in the airplane and fly. Those particular problems on 9/11 prompted the system we have in place today with aircraft armed and pilots basically sitting in the cockpit ready to go. Can you explain what you are wanting to know a little better?

@RonBeyer -- I'm wondering why it was said that the jet was completely unarmed, more or less...

@UnrecognizedFallingObject The training slugs, while damaging, aren't missles. Modern airliners are a lot like flying beer cans, and contrary to popular movies, a few bullets most likely won't make the plane explode. With partial magazines all they may end up doing is disabling the plane, its still 120 tons of flying (or gliding) destruction.

@RonBeyer -- however, crippling the airplane could very well be sufficient to thwart the terrorists' intended objective.  It does raise an interesting question though: if the pilots did have to pull the trigger, where should they have aimed?  A widebody is a relatively large and non-maneuverable target from an aerial gunnery standpoint, so the idea of the "back" pilot being able to set up a shot on some region of the aircraft (instead of simply aiming at the plane as a whole) isn't too far-fetched in my mind at least...

@UnrecognizedFallingObject As a wild guess I would say target either (a) the cockpit, or (b) the engines. If you can do sufficient damage to the fan disc the engine will cease operating (and it doesn't take too much to be "sufficient" in this context), otherwise shooting up the cockpit will at least cause decompression & hopefully incapacitate the pilot. You now have a runaway plane, but at least not one actively attacking something...

The question is about military tactic (why the aircraft were not armed?), not about flying. It doesn't seem on-topic.

If the article is to be believed, the gun was probably loaded with M55A1 training rounds which are a steel core projectile with an aluminum nose-cap used for target practice as opposed to the M56 HEI or M53 API rounds which the jet would go to war with.  If it had either a full or partial magazine of the M55 ammunition, it would have had at least some firepower available to it, but I imagine the crew had resolved themselves to, if necessary to protect Washington DC, ramming their aircraft into the jetliner.  It just goes to show you how utterly unprepared this nation was for that kind of a ruse.  Its obvious that this was an anomalous and desperate measure by two very brave ANG pilots who responded to a call using whatever resources were available to them.
Post 9/11 most fighter bases in the nation keep at least two birds housed in a Hardened Aircraft Shelter (HAS) in a 'hot' condition, that is, fully fueled, 520 rounds, 2 x AIM-9s, 2 x AIM-120s, with the INS aligned and two pilots keeping watch round the clock for the alert.


text:
Is there a cockpit which can recognize the voice of the pilot and help him/her to fly?
Is there any new cockpit that uses voice commands (think for example Siri from the new iphones) that can identify the voice of the pilot and help him/her to fly?

Pilot speaks to co-pilot  "I would hate to have been on that flight that descended at 15000 feet per minute".  Auto-pilot to crew - "Roger"

@Simon Pilot to AP: Go-Around, Go-Around! - AP replies with Siri's charming voice: Sorry! I didn't quite get that. Should I start a web-search for "Ground"?

@Simon That reminds me of a Dilbert cartoon. Dilbert says he's installed new voice-controlled software on his computer. Wally replies something like, "Wow. I hope you don't accidentally DELETE ALL YOUR FILES!"

The currently selected answer ("No") may be not current, another one from Adrian states that the Typhoon is fitted with voice-recognition. Actually the voice is used to command 20+ non-critical fucntions.

Yes...kind-of.
There was a product by a company called VoiceFlight which would allow you to program Garmin GPS systems (GNS 430/530), which was FAA-approved by STC for a good number of light General Aviation aircraft.
While it was not capable of flying the plane by voice instruction it could be used to program a route into the GPS, which a coupled autopilot would then be able to fly.
The VoiceFlight product has been discontinued as competition from the newer GTN 650/750 (which require less knob-twiddling to program a route) and other technologies like Connected Panel ate into the company's business to the point where it was no longer viable to remain in business, but the core idea of voice technology in the cockpit has been proven possible (and according folks who tried it, even practical). It may make another appearance some day.

No, voice recognition is currently not used in aircraft as it would have to be built into the aircraft to pass certification for the aircraft and with rotating crews on aircraft, the voice recognition would need to be able to work with too many different voice types: high pitch, low pitch, male, female, accents, dialects and many more factors.
Voice recognition works because it learns from the user over time, something that is not possible in a cockpit environment with crew resource management.
There is a prototype in development by Honeywell at the moment, but it's in early stages of development.
Related reading:
The benefits of a Speech Recognition enabled cockpit by AdacelPDF

Voice recognition works because it learns from the user over time, something that is not possible in a cockpit environment with crew resource management. I would take exception with that statement - have you used Siri on an iPhone or Google Voice on an Android phone? They work fairly well for most people. That said, I still wouldn't want to trust the lives of a fully loaded A380 on Siri's abilities just yet.

Don't Siri / Google Voice work based on the recording being sent off to a processing unit somewhere at Apple's or Google's? Siri for sure does not work offline, never used Google Voice. ClassicVoice Recognition works because it identifies patterns and matches them. Since an Airbus does not have an internet uplink, I assume classic pattern matching in my answer.

@SentryRaven: Google-anything works online only. Voice is not an exception.

True, GV does send the data to Google, but it does work for most people's voices. Again, not disagreeing with the general point that it's not good enough to trust lives to yet, just that it's getting close, fairly quickly.

@FreeMan Siri and GV work because the device itself is not processing the data, but the data center, which has far better capabilities and millions of "training" with different voice types and speech. We will get to that point at some place that devices will be able to handle this, but as it currently stands and how I worded my answer: It's currently not feasible.

Siri sends data off for additional processing, but Apple's "voice command" system for the iPod app processes your speech locally (or at least it used to). It had a much less sophisticated set of commands than what Siri can try to interpret, but in my limited experience fighting with Apple voice recognition it tended to do a better job with song titles than Siri does.

At the point that voice recognition does start to become incorporated in cockpits, it will surely be used in non-critical applications first: "OK, airplane, get ATIS for K-O-R-D."  If it retrieves the weather for Timbuktu instead, no big deal.  Then after that system is working well, the next step might be some limited inputs into the FMC, which (like manual inputs today) wouldn't take effect until the pilot (and, really, the other pilot also) reviews them on the screen, agrees, and presses the "Execute" button.

Yes - Typhoon uses a "Direct Voice Input" (DVI) system. This has a limited vocabulary which allows the pilot to control non-safety critical items via voice input. The current system uses an uploaded template specific to the pilot to enable recognition. Although developments are looking at various updates including removing the dependency on pilot templates.


text:
What is the highest muzzle velocity of a gun on any fighter aircraft?
I'm looking for the greatest muzzle velocity of a gun on any fighter aircraft.
I looked up the GAU-8 Avenger from the A10 Warthog first. Its muzzle velocity is 1,070 m/s, which is pretty darn high (almost 3 times the speed of sound). Are there any faster bullets out there from an aircraft gun?
Note: Don't really care about the firing rate (rounds per minute), or bullet caliber. All I'm looking for is highest muzzle velocity.

BK 37 apparently had 1170 m/s muzzle velocity with APCR ammunition. Hans Ulrich Rudel who was a consultant for A10 used fly a Stuka equipped with one. So it seems a legit case of "weapon with similar power to GAU-8". Although rate of fire was much lower.

The muzzle velocity of guns is based on multiple factors and generally sees a wide range. Most importantly how the bullet is loaded (gun powder wise) and what mass the bullet is. For example the P-51 mustang carried 6 50 caliber BMG's (M-2). Which (although not available at the time) is capable of accepting the Caliber .50, Saboted Light Armor Penetrator, M903 round which has a quoted muzzle velocity of 4,000 ft/s (1,219 m/s). It should also be noted that the base muzzle velocity of an M2 is 2,910 ft/s (890 m/s) for M33 ball round. So it really depends what round you are loading in.
The F-35 Joint Strike Fighter has the GAU-22 Gatling Gun which with the TP HEI ammunition has a quoted muzzle velocity of 3,560 feet (1,085m) per second (15 m/s faster than the GAU-8 on the warthog).

(Not sure about you guys but I often test my gatling guns with my multi-meter...)
image source

Technically the P-51 carried 4 or 6 M2 .50s, not 2 :)

Dave, can you provide a source for the image? (Image Attribution)

Edits made, thanks guys.

Fine answer ... except the image, which seems to be decorative at best.

that is an image of the GAU-22 the gun (and F-35) in question, granted a bit humorous it is still on topic.

The guy with the multi-meter is in the GD brochure: http://www.gd-ots.com/armament_systems/GAU-22-A.pdf

Why is the plane's engine seemingly not running? (Obviously the guns and multimeter guy are photoshopped in; was the plane added as well?

authors: Велислава Пенева


text:
Why is taxiing super slow after an ILS CATIIIB landing in almost zero visibility?
I have experienced my very first ILS CAT IIIB automatic landing at my own home airport Lucknow (VILK). I'm super excited but also have myriads of questions related to many unique procedures I saw which I never seen in all my years of flying. Even though I was happy to have experienced such a magical landing, I was afraid how are we gonna park now because it was all white and the taxiing on this flight was the literally the slowest taxiing I have ever seen in my life.
After we landed and I could barely see the taxiway markings and even the runway borderline was hard to see. We crawled to the end of the runway to make a 180 degree and backtrack to vacate via taxiway C. The plane had already slowed down on its initial landing roll and at that time I didn't know about any special procedures or anything like low visibility conditions.
I was wondering why we did not exit via Taxiway B or C or even D or E when we had so many chances to do so and why we had to come all the way to the end of the runway only to go back and exit via C again and park at bay 13?
If any pilots here who have flown in CAT IIIB conditions, I wanna know how hard it is to find the taxiways in such a thick fog?

What type of airplane were you aboard?

The reason for using taxiway C is described in the Low Visibility Procedures from the AIP:

4.4.4 At present, TWY ‘C’ and Stand no 11 to 14 are equipped with CAT IIIB lighting system as per short term interim plansubmitted to DGCA by AAI and agreed to by DGCA vide letter no. AV.20015/09/08-AL dated 15-07-2014. Therefore, duringCAT IIIA and CAT IIIB operations, arrivals and departures shall use TWY ‘C’ only.

So the reason you had to taxi via C is because C is the only taxiway with sufficient lighting to support CAT III operations. For CAT III operations, taxiway centreline lights are required. The other taxiways at Lucknow only have taxiway edge lights.
Source: https://aim-india.aai.aero/eaip-v2/eAIP/EC-AD-2.1VILK-en-GB.pdf
The reason you had to backtrack (turn around on the runway and taxi back in the opposite direction) must be that the plane was not slow enough to vacate via C when you passed it the first time. I know you said you had already slowed down, but in thick fog it can be pretty hard to estimate speed, especially when looking out a side window. The pilots obviously have access to precise instruments, and must have determined that the aircraft had not slowed down enough.

Thanks a lot for your answer sir..I have all the answers now regarding my first ever CATIIIB flight..I considee myself so lucky that I got to experience this magic of the most advanced ILS on planet !! I hope all avgeeks one day experience it too..its a magical feeling !


text:
Which air traffic controller is responsible for a taxiway between parallel runways?
When an airport use two runways that are parallel at the same time, my question is which tower controller owns the "ground space" between the runways?

Typically, neither. A separate controller, "___ Ground," controls taxiing traffic. On a big enough airport such as Denver (KDEN) or Atlanta (KATL), there may be more than one ground control, each on its own frequency. Their domains are split geographically: one controls east (DEN) or north (ATL) of the terminals, while the other controls west or south.
At some airports, though, a single Tower frequency owns both parallel runways, for example Austin TX (KAUS), and in San Francisco, one controller works all four runways (1L/R and 28L/R). No rookies working that position!